1. Field of the Invention
The present invention relates generally to data transmission/reception in a broadcast or communication system, and in particular, to a method and apparatus for efficiently recovering data, even when data loss has occurred over a channel or network.
2. Description of the Related Art
With the increased consumption of multimedia content, e.g., high capacity multimedia data such as High Definition (HD) and Ultra High Definition (UHD) content, network data congestion is more common, which deteriorates broadcast and communication environments.
Consequently, content data transmitted by a sender (e.g., a Host A) may not be normally delivered to a receiver (e.g., Host B), resulting in data loss on a routing path. In many cases, data is transmitted in packets, and thus, data loss also occurs in packets. The data loss on the network causes data packet reception failure of the receiver. Further, it is difficult for the receiver to recover the data carried in the missing packet. As a result, the missing packets cause audio and video quality degradation with various mal-effects (such as a cracked screen, missing subtitle, file loss, etc.), thereby inconveniencing a user.
A well-known missing data recovery technique is to group data packets, i.e., source packets, with various lengths into source blocks and add repair information, i.e., parity bits or repair packets, to the source blocks thorough Forward Error Correction (FEC) encoding. When there is missing data, the receiver is then capable of decoding the original data using the repair information.
However, when the length of the source packets constituting the source block is variable, the source block may be partially filled with zero padding, and sometimes, a relatively large amount of zero padding, depending on the source block configuration and packet length. The zero padding carries no information but increases the number of symbols in the source block, which gives the same effect of transmitting unnecessary parity.